Circuits & Schematics: metal detector - 2

11. A simple, accurate, and efficient charge pump voltage inverter for $1 (in singles)
    Circuits Supply Texas Instruments CD4053B
    .. IN . Under load, it will decline at ~160 mV/mA (Figure 3). If operation at higher V IN inputs (up to 10 V) is required, the metal-gate CD4053B can be employed. Of course, capacitor voltage ratings would need to be correspondingly higher. ...
    10-01-2024

12. Bridge measures small capacitance in presence of large strays
    Circuits Measurement Analog Devices LT1004 LT1413 LT1462 LTC1043
    .. capacitances, especially if the sensor is remotely placed. I needed to make measurements with a 50 pF cryogenic fluid level detector, with only 2 pF full-scale change, hooked to several hundred pF of varying cable capacitance. This ...
    18-12-2023

13. Force/sense connection eliminates multiplexer on-resistance error
    Circuits Amplifiers Analog Devices LT1028
    .. high-performance bias and preamplifier circuit for a cryogenic (liquid-nitrogen-cooled), mercury-cadmium-telluride infrared detector. These broadband, photoconductive optical sensors are popular in IR spectrometers. They are particularly ...
    08-12-2023
14. Exclusively select 1 of N relays
    Circuits Supply ECE EDR2
    .. “one and only one” function is often implemented as mechanical switches in which an actuator (usually a movable metal bracket) is used to switch contact groups on and off. When any switch is pressed, this bracket first ...
    24-11-2023
15. Circuit forms satellite-dish command decoder
    Circuits Signal Processing, Filters Microcontrollers Usage TV
    .. eliminates the need for external memory. The only external components are a few discrete devices for the signal detector and the coaxial-cable loop-through (Figure 2). You can add an RS-232 driver if you want to display the ...
    09-11-2023
16. Simple night-light uses a photoresistor to detect dusk
    Circuits Automation Beginners Light Analog Devices AD8214
    .. can use an LDR in a circuit that detects darkness and turns on an LED (Figure 2). The circuit uses a high-voltage threshold-detector IC that features a current output and operates as a comparator. The LDR and potentiometer R 3 form one ...
    24-10-2023
17. Adjust op-amp gain from -30 dB to +60 dB with one linear pot
    Circuits Analogue Design Amplifiers Analog Devices OP37
    .. GIGO gain versus R2 wiper position 0 to 1 = fully CCW to fully CW. To optimize noise performance, R1 and R3 should be metal film types to avoid carbon-resistor excess (1/f) noise, and R2 should be a cermet type. Materials on the topic ...
    24-10-2023
18. A long pulse detector circuit
    Circuits Analogue Design Signal Processing, Filters Texas Instruments LM393
    .. longer than the set width are to be detected, ignoring the other short pulses. We are familiar with the missing pulse detector circuit, which detects the occurrence of a missing pulse in a pulse train where the pulses are of equal ...
    17-10-2023
19. Circuit's RMS output is linearly proportional to temperature over wide range
    Circuits Measurement Analog Devices LT1001
    .. diode switching response becomes sluggish. Several readout enhancements are possible. For example, connecting a unity-gain detector or precision full-wave rectifier [2] to the filter output allows an output that is positive with ...
    03-10-2023
20. Make gain-control multiplexer R_ON and R_OFF errors (mostly) disappear
    Circuits Analogue Design Texas Instruments CD4052B TLV2371
    .. mux R ON values run from 100 to 1000 Ω, tend to vary significantly with fabrication process (e.g., polysilicon gate vs metal) signal level, supply voltage, and temperature. Because they are electrically in series with the resistors, ...
    28-09-2023

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